Tropical and South Atlantic response to volcanic forcing and its impacts on the hydroclimate variability of South America

Abstract

Large volcanic eruptions can affect the global climate through changes in atmospheric and ocean circulation. Understanding the influence of volcanic eruptions on the hydroclimate over monsoon regions is of great scientific and social importance. The South America Monsoon System (SAMS) is the most important climatic feature of the continent. Both the Intertropical and the South Atlantic wind convergence zones (ITCZ and SACZ, respectively) are fundamental components of the SAMS. They show variations on a broad range of scales, dependent on complex multi-system interactions with the adjacent Atlantic Ocean and teleconnections. Also driven by the winds, the Atlantic Subtropical Cell (STC) is the link between the subduction zone in the subtropical gyre with the tropics. Hence, the Atlantic STC influences equatorial sea surface temperature variability mostly related to strength and duration of the upwelling along the equator. This occurs on interannual to decadal scales in the tropical Atlantic Ocean, which may be relate to the Tropical Atlantic Variability (TAV) modes. In order to improve our understanding about the responses of the Atlantic Ocean-atmosphere system to the volcanic forcing, we aim to identify the dominant mechanisms of seasonal-to-interdecadal variability of the Atlantic STC, how it is connected with the TAV modes and, therefore, understand how the South American hydroclimate responds to these processes. We propose to identify the dominant mechanisms in the Coupled Model Intercomparison Project 6 (CMIP6) historical simulations, then investigate responses after large Pinatubo-like (1991) and Tambora-like (1815) eruptions relying on the VolMIP (Volcanic Forcings Model Intercomparison Project) experiments. (AU)